The COVID-19 vaccine is rapidly approaching the point where it can be distributed globally. However, as the supply of vaccines increases, the distribution process needs to consider how best to distribute vaccines equitably between countries and within those countries. This is particularly important in lower income economies where the reaction to the pandemic has been less pronounced. The current approach to distributing vaccines is based on an arbitrary allocation scheme that prioritizes those at highest risk of disease and death, but that may be unfair to low income populations who have a greater chance of getting the vaccine and avoiding illness or suffering from severe disease.
Vaccine distributions are complicated by the fact that some groups have a greater propensity to get the vaccine than others and that there are many factors that can affect vaccine uptake. Amongst these, the factors with the largest correlation between country-level vaccination uptake and other country-level factors include early procurement, domestic production of vaccines, and countries’ health infrastructure. Vaccine distributions also depend on the extent to which population groups exercise self-protection by limiting their person-to-person contact.
Vaccine prioritisation strategies can be used to help determine how and when to distribute vaccines. For example, a strategy that focuses on vaccinating those with high mortality per infection first is superior to no prioritisation at high vaccination rollouts, while focusing on vaccinating the oldest first is moderately better when rollout rates are slow (0.25%/day) and coverage is high (e.g. 80%). A dynamic RbPAD strategy performs similarly to the best single call strategies, both by age and interactions, but is model independent and computationally efficient.